Clinical studies indicate a great need for monitoring core temperature throughout the perioperative process at a desired accuracy of <0.5oC. Accurate and fast detection of core temperatures beyond the intended ranges can decrease the likelihood of adverse effects, the outcomes of which may range from increased hospitalization costs to patient fatalities (e.g., during malignant hyperthermia). Unfortunately, current means of measuring core temperature present a tradeoff between invasiveness and accuracy and suggest a need for exploring novel solutions. Gold standard esophageal, nasopharynx and pulmonary artery thermometers are invasive and not feasible for all surgeries nor pre-/post-operatively; skin surface thermometers do not reflect core temperature and are affected by the environment; zero-heat-flux thermometers are unsuitable for intense body temperature changes and do not work for deep hypothermia; and state-of-the-art radiometers are inaccurate by 1oC to 2oC at best, and, hence, clinically unacceptable. The goal of this research is to explore the feasibility of an alternative radiometry technique that leverages innovations in broadband measurements, forward modeling of layered tissues, and dry biomimetic antennas to enable non-invasive, accurate, and real-time core temperature monitoring. The hypothesis is that low and high frequencies will infer the temperature from across deep and near-surface tissues, respectively, and that their post-processing will provide accurate measures of core temperature (within 0.5oC), in real-time, and across any temperature range of interest, as validated upon head- emulating phantoms. This study is significant because it reveals previously nonexistent knowledge on wideband radiometer models/algorithms and antenna designs for non-invasive and accurate core temperature monitoring. This radiometer is envisioned to be a much needed addition to the operating room, across the perioperative process, and beyond (e.g., cancer diagnostics). The expectation is to eventually link the device to other non-invasive monitors (e.g., cerebral oximeters in cardiac anesthesia) towards the development of new markers for more reliable and timely detection of complications. In Aim 1, wideband radiometry models and antennas will be developed. The focus entails translating models that have been successfully implemented in the past for inferring the temperature of layered ice sheets into layered head media. Such models have never been used in the context of medical radiometry. Optimal frequency ranges will then be identified, and biomimetic antennas will be designed to accommodate this bandwidth while exhibiting unprecedented radiation efficiency. In Aim 2, our integrated radiometer will be validated upon head phantoms that accurately emulate biological temperature flow and dielectric properties. Biomimetic antennas will be fabricated, connected to radiometers, and used to validate: a) the brightness temperature spectrum obtained from modeling, and b) the hypothesized accuracy of 0.5oC in retrieving the core temperature. Feasibility of this wideband radiometer in tissue-emulating phantoms will form the basis of future studies on human subjects.